


Ocean Blue

by ArchangelUnmei



Category: Final Fantasy XV
Genre: Alternate Universe - Merpeople, Body Horror, Gen, Human-to-merperson transformation, Implied/Referenced Character Death, It's not heavily described, M/M, Plot going on in the background that I'm never going to explore, Pre-Relationship, The characters don't find it horrific but readers might so tagging just to be safe :), Transformation
Language: English
Status: Completed
Published: 2018-02-21
Updated: 2018-06-20
Packaged: 2019-03-22 07:11:45
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 6,318
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13758948
Author URL: https://archiveofourown.org/users/ArchangelUnmei/pseuds/ArchangelUnmei
Summary: Everyone in Altissia knew about the Tidemother's Children, but Prompto didn't know anyone who'd ever seen them in person.





	1. Chapter 1

**Author's Note:**

> Written for an AU Mixup challenge over on [Tumblr](http://archangelunmei.tumblr.com/post/171139457044/hospital-mermaids-steampunk-au-with-noctis-and). The prompt was for mermaids/hospital/steampunk. Uh. It's not very steampunk-y and they don't get to an actual hospital but I like it anyway so here. XD
> 
> And I know I left it in a terrible place, but for now this is all there is. My sincerest apologies.

It was dark in Altissia these days.

The government had stopped bothering to refill the street lamps with oil months ago, and most houses kept their windows tightly shuttered against the night, thick curtains making sure that no light leaked through into the misty streets outside. 

That was fine with Prompto. He didn't mind the dark, and it was easier for him to move in the shadows, scraping what he could off of Altissia's underbelly to survive. He kept company with the waves lapping against the sides of the canals and the occasional splash of stones tumbling into the water. 

It was late, well past dusk and far until morning, and he was carefully making his way back toward Aranea's when he saw the light. 

He was on one of the higher bridges, and the light shone dim blue from the mist of the canal below. Prompto stopped, peering downward in puzzlement. It couldn't be an odd gas lamp, even the most unreliable of those had a warm orange flame. The cops' preferred charge-guns tended to glow green, and bootleg ones were usually yellow-green or dramatically bright red. Prompto's own preferred weapons were analog guns with no lights because he wasn't an _idiot_. But he couldn't think of anything off the top of his head that would glow a clear, pure blue like that. 

"It's a trap..." he muttered to himself, a soft sing-song imitation of Aranea's favorite phrase. But even as he chastised himself, he was already finding a stairway down to the canal's edge, craning his neck to keep the glow in sight. As he got closer, he realized it was even lower than he'd thought, not beside the canal but actually _in_ it and- 

He stopped, and stared. 

Clinging to the crumbling stone lip of the canal were two men. Their hair was dark, wet and blending into the dark water below them, their skin slick and pale. One of the two, his hair quite a bit longer and plaited into elaborate braids, was supporting his smaller (younger?) companion, who was sagging against him and seemed almost unconscious. The one with the braids had one arm slung up across the stones almost at Prompto's feet to hold on, giving him a good look at the lines of luminous scales that streaked up his arm from wrist to shoulder, the wickedly sharp talons at the end of his fingers. They had _fins_ too, fanned out from both sides of their heads where Prompto had ears, and he could just see what looked like larger fins down the spines of their backs, also glowing with that same blue light. 

He couldn't help noticing that the younger one - the hurt one? - was glowing quite a bit more dimly. 

At his approach, the braided one's head jerked up, eyes glowing brightly in the darkness and lips curled back in a snarl that revealed needle-sharp teeth. Prompto stopped so fast he almost skidded across the wet cobblestones, heart pounding as he unwittingly imagined those teeth tearing into him. Everyone in Altissia knew about the Tidemother's Children, but Prompto didn't know of anyone who'd personally seen them. Legend said that's what happened if you worshiped Leviathan _too_ fervently, that She might decide She liked you and transform you into a half-serpent creature to serve Her in the depths of the ocean. 

Prompto swallowed hard, but his eyes slid back to the other merman. "Is... Do you need help?" 

The one with the braids eyeballed him, clearly distrusting, but also clearly out of options. "Yes," he said finally, his voice rougher than Prompto might have expected, but then again how often did creatures living underwater really have need for speech? 

Prompto took a deep breath, squared his shoulders. "Okay. I have a friend, she's a doctor. She's never treated one of... um, your kind before, but..." 

"He mostly needs rest. Is your friend near the water?" 

Prompto nodded. "This way, it's not far." He led the way, and the two kept pace in the canal, more quickly than Prompto expected considering one of them was near unconscious. It was only another block or two before he could step up and knock on Aranea's door, sheltered under the shadow of a wide bridge. He winced a little at how bright that made the mermen's glow seem, but it was late and the streets were mercifully empty. 

Despite the hour, when Aranea opened the door she looked alert, her gun-lance held easily against her shoulder. She relaxed further when she saw it was only Prompto, but he shook his head before she could invite him in. "They need help, 'Nea." 

Aranea looked past him, to the blue glow in the canal, and asked no questions. 

The younger merman was heavier than Prompto expected as he and Aranea took him by the shoulders and started to haul him up. As more of his body left the water he finally stirred, tail thrashing weakly in the water. "Nyx-!" 

"Shh," his companion, Nyx?, reached out to take his hands, squeeze them until the younger one opened his eyes. His expression was glassy and dazed, but locked onto Nyx's familiar face. "I'm right here, Noct. I'm going back for Luna, but I'm leaving you with friends. Alright?" His eyes flicked up, met Prompto's, then Aranea's, and Prompto found himself nodding, Noct's skin feverish under his hands. 

Friends. 

"I'm Prompto," he told Noct as he and Aranea finished pulling him out of the water. Prompto shifted to take his shoulders alone as Aranea circled around to lift his surprisingly long tail so they could carry him inside and out of sight. When Prompto glanced back, Nyx was gone and the canal was dark. 

They got Noct into Aranea's bathtub for lack of anything better, but it seemed to be enough. Noct fell into a fitful sleep almost immediately, and Prompto collapsed to sit on the floor beside it. 

"What the hell?" Aranea shook her head, murmuring more to herself than Prompto, and Prompto could only shrug. 

He had no idea what was going on, but he had a feeling it was going to get really, really complicated. 

Without really thinking about it, he reached out to take Noct's hand.


	2. Chapter 2

Noct slept for three days, and in that time Prompto and Aranea tried to come up with a plan. 

Aranea had examined him as best she could, checking his shoulders and ribs to make sure they were sound, running her hands along his tail to feel for any unusual-seeming lumps or grating bone. His fins all seemed to be alright too, none of them were torn and they continued to glow softly blue. He had gills, pinkish-red lines along his sides, just below his rib cage, but at the moment they were sealed shut, his lungs supplying him with oxygen instead. He was only half-submerged in the water, his tail curled awkwardly and the end of it flopped out over the side, but he didn't seem to mind that either. He slept through it all, head tipped back against the edge of the tub and making tiny snoring sounds. 

"We could go find one of the Tidemother's Priestesses," Prompto suggested, sitting at the kitchen table disassembling and cleaning his favorite gun to keep his hands busy. It was better than pacing back and forth endlessly like Aranea. It was day three, and despite keeping a close watch on the canal, Nyx hadn't returned. Once or twice Prompto thought he'd seen flickers of blue, moving fast, but nothing had surfaced. It was probably just his hopeful imagination. "They've got to know the Children are real, right?" 

"Maybe," Aranea pursed her lips. "But if they do, why didn't Nyx take him straight to the temple? Or ask us to, if he didn't have time?" 

Prompto shrugged helplessly; he didn't have an answer. 

Suddenly, a knock came at the front door, and they both tensed. Prompto looked down at his disassembled gun and gave a little frustrated hiss. Aranea grabbed her gun-lance from its place, holding it ready as she gestured for Prompto to get the door. 

Standing on the front step, lips pressed into a thin line of anxiety, was a man. He looked... normal, his clothes nothing remarkable, his hair combed up into a fairly typical style. He was wearing glasses, and perhaps the most remarkable thing was that they were _just_ glasses, no tech built in that Prompto could see. He was wearing gloves on both hands, and clutching a small scrap of paper on which Aranea's address turned out to be written. When he spoke, his accent was crisp and vaguely Tenebraen. "I'm told there's a doctor here?" 

"Not me," Prompto gestured, and Aranea stepped into the door frame. Prompto quickly slid around behind her, taking the gun-lance from her other hand so it would stay out of the visitor's sight. He might be a perfectly normal person honestly seeking a doctor, but then again he might not. Better safe than sorry. 

"You need a doctor?" Aranea asked coolly, leaning in the doorway in such a way that it left Prompto with a clear shot - just in case - and also made it clear the visitor was not invited in. 

He frowned a little, pushing his glasses up his nose, and glanced back and forth to make sure the street was clear. Prompto's finger inched a little closer to the trigger, because _that_ wasn't suspicious at all. 

"...Not me," the stranger finally murmured, his voice pitched low. He met Aranea's cool gaze squarely. "My friend told me you're hosting a visitor from out of town." 

Aranea frowned in mistrust. "We might be, but I'm not sure it's any business of yours." 

"That's fair," he pushed his glasses up his nose in what Prompto recognized was probably a nervous habit. "But he's a friend of mine. Things are going on that you're not aware of, he's going to need a familiar face when he wakes." 

"If you're his friend, what's his name?" Prompto asked. 

"Noctis," the stranger replied without a second of hesitation. 

Prompto and Aranea exchanged a long look. They were very practiced at it by now, communicating a lot with the barest eye contact and some flicked hand gestures. Prompto tilted his head slightly, and Aranea sighed and stepped back. "You might as well come in." 

"Thank you." He waited until Aranea had closed the door behind him, holding his hands open and loose at his sides. He didn't look particularly surprised when he saw Prompto had the gun-lance at the ready. If anything, he looked slightly amused, though it was hard to tell when his face didn't move. "My name is Ignis." 

"I'm Aranea," she said coolly, sweeping around Ignis' side and plucking the gun-lance out of Prompto's hands, checking it over before flicking the safety back on and leaning it back into its rack. Prompto didn't protest; Ignis looked like a twig, and if he ended up a problem he and Aranea could probably take him bare-handed. "And this is Prompto. How is it you know Noctis? Go swimming often?" 

Ignis might have smiled very slightly at her sass. "Something like that." 

The apartment wasn't very big. They all heard the slight slosh and splash of moving water, and Ignis spun as though he was being pulled on a string. He moved without glancing at either of his hosts, striding toward the bathroom and leaving the other two to trail after him. Even from the back, Prompto saw his shoulders relax when his gaze found Noctis in the bathtub. 

"Noct," Ignis crossed the small room and knelt, taking the merman's hand in both his own. "Can you hear me?" 

Noctis stirred again, the long fins at the end of his tail twitching a little where they trailed across the cold stone floor. His shoulders shifted restlessly against the curved edge of the tub, and his fingers curled a little around Ignis'. Then his eyes fluttered open, though he still looked dazed. "Iggy?" 

"None other," Ignis pressed Noctis' hand to his forehead in relief. "Iris brought me word about what happened. I'm sorry I didn't come find you sooner, but I've been busy making arrangements to get you to the Quay." 

"Galdin Quay?" Prompto blurted in surprise, still hovering in the doorway. He still had no idea what was going on, only a handful of puzzle pieces and no picture on the box. "Why are you taking him to Galdin?" 

Ignis half-turned to look at him, eyes narrow in distrust, but it was Noctis who answered. He still sounded sleepy and dazed, but his eyes were glowing again when he tilted his head back to look at Prompto over Ignis' shoulder. 

"Retreat. My uncle staged a coupe, and I'm not strong enough to fight him yet." 

"A coupe?" It was Aranea asking this time, her own eyes narrowed, and Ignis sighed. 

"Noctis is the rightful High Priest of Leviathan, and the natural leader of Her Children. His uncle has decided to take that position for himself." 

"Oh," Prompto's eyes went a little wide. "Wouldn't the Tidemother, um. Protest that?" 

"You would think," Ignis said, frostily enough that Prompto swallowed and decided not to ask again. When he stayed silent, Ignis turned his attention back to Noctis. "The others will meet us there. If you don't feel strong enough to swim that far, I've managed to acquire a boat that has room for a tub." 

"You can't exactly carry him on your own, Specs," Aranea pointed out, ignoring the glare the nickname earned her. 

Prompto nodded. "Let us come with you." 

Everyone stopped to stare at him, and he flushed. He'd _meant_ to say 'let us help', but there it was. He and Aranea neither one had much tying them to Altissia. A change of scenery might mean a chance at a new start, merpeople aside. 

"We'll need more feet on land, Iggy," Noctis said softly after a moment, reaching out to touch the back of Ignis' gloved hand lightly. 

Ignis quickly drew his hand back from his touch, but sighed and reached up to adjust his glasses again. "...I suppose we might, at that." 

~*~

They arrived at Galdin Quay in the middle of the night. 

The sky was bright with a million stars, and Prompto hung over the side of the boat to marvel at the glowing spots of the barrelfish that lurked under the water. Behind him, Aranea and Ignis were arguing about how best to bring the boat around to the dock, but it didn't sound like they were about to come to blows, so Prompto wasn't too concerned. Under the little covered area of the deck, Noctis was glowing softly in his tub, fins twitching with impatience to be back in the water. 

As he stared into the water, Prompto realized that some of the blue lights were moving too fast to be barrelfish, keeping pace along with the boat. He blinked, squinting, and yeah, they were definitely being paced by a couple merpeople. As if they knew they were being watched, they drifted a little closer to the surface, enough that Prompto could make out the flick of their tails, the paleness of their torsos. 

"Uh, guys?" He called out. "We've got company in the water." 

Noctis straightened up with a splash, but he couldn't really go anywhere without help. Ignis left the helm to Aranea and came to Prompto's side, moving faster than Prompto had seen before as he leaned over the side. 

Below, two merpeople broke through the surface of the water. Neither of them was Nyx, though they both followed the pattern of dark hair and bluish fins, though theirs tinted a little more green than Noctis' or Nyx's. The larger of the two had broad shoulders and an impressive scar over his chest, which somehow managed to mostly miss the impressive, intricate squid tattood across his shoulder, the tentacles extending down and around both arms. 

The other, smaller one was a girl. Or Prompto thought she might be a girl, anyway. She was much slighter than any of the other three Prompto had seen so far, and she was wearing an elaborate collar-style necklace of shells that matched the bracelets around her wrists. Her fins were bigger in proportion to her body, and had wicked-looking spines that the males seemed to lack. And she wasn't actually wearing a shirt, Prompto noticed with embarrassment, and gulped. 

"Gladio," Ignis breathed beside him, like he was saying a prayer, and Prompto glanced over at him. He was shocked to see Ignis actually smiling, soft and relieved and strangely giddy. "Thank the Mother." 

And then before Prompto could react, he reached down to yank off his stiff-soled shoes, and then vaulted over the railing to drop three meters into the ocean, clothes and all. Prompto stared, stunned, as the tattooed merman snatched Ignis up into his arms and rolled over in the water, soaking him thoroughly before bringing him up for air again, Ignis laughing as he wrapped arms around his neck and kissed him. "Uh... Noct?" 

When he glanced over his shoulder, Noctis was leaning against the edge of the tub, looking both amused and relieved. "Big guy, squid tattoo?" He grinned when Prompto nodded. "That's Gladio, my Shield. I'm so glad he got away. Is there anyone else with him?" 

He looked so anxious, still worried about friends and family he hadn't heard from in the chaos surrounding his uncle's attack. Prompto's quick to reassure him with a nod. "It's a girl - I think? Do you guys have girls? Small, short dark hair that kinda flips at the ends, spines in her fins, really pretty pink shell necklace?" 

"Iris," Noctis looks a little relieved again. "That's Gladio's sister. Aranea!" He raises his voice a little, tail flipping in impatience. "Get us docked already!" 

"Working on it, Princess!" she called back, cheerfully irreverent. 

Prompto glanced back into the water when there was another splash. Gladio was supporting Ignis easily with an arm around his waist to keep him above the water, and now two more merpeople had broken the surface on either side of them. One was Nyx, and the other was completely different than any of the others. 

Her tail was silvery-white, her fins almost translucent except for the solid barbs of her spines. Her hair was pale too, silver blond and braided into an elaborate style with what Prompto swore was a crystal and coral _crown_. She wasn't wearing a shirt either, but Prompto was too busy staring at her ethereal beauty to notice much. 

He finally managed to tear his eyes away when Noctis called his name. "Uh, Nyx is back, with a really gorgeous mergirl with a white tail?" 

Noctis' expression changed, looking relieved and determined all at once. "Get over here and get me out of this. That's Luna. She's not mer, she's a siryn." 

"There's a difference?" Prompto didn't think this was going to work very well, but he crossed the deck and crouched a little to let Noctis wrap his arms around his neck. "Oh Astrals, why are you so heavy?" 

"You call us Leviathan's Children, right?" Noctis hitched himself a little higher up Prompto's back, making Prompto grunt as the full brunt of Noctis' weight dragged at him. "We're not. But Luna _is_." 

Prompto was so surprised he almost dropped Noctis, and only the merman's hiss in his ear kept him steady. He took a couple steps away from the tub, the end of Noctis' tail dragging across the smooth wood of the deck behind them. "What, like _literally_ -" 

"The Tidemother's daughter, yes." They were close enough to the rail that Noctis wiggled, waving a hand, and there were cries of relief and delight from everyone down below. Prompto maneuvered around and basically dumped Noctis backward over the rail, making him squawk. His tail smacked Prompto's arm on the way past hard enough to leave a bruise, but it was worth it. 

He leaned against the railing, watching with a grin as Luna and Iris both practically tackled Noctis to hug him. He hugged them both just as tightly in return, and whined when Gladio reached over to ruffle his hair, his other arm still wrapped possessively around Ignis. 

Nyx looked up to meet Prompto's eyes and mouthed a 'thank you'. Then he raised an eyebrow, tilting his head in an invitation. 

Prompto took a deep breath, looking out across the water. The night was warm and bright, Noctis was laughing, and there were more lights approaching them under the water. Aranea was swearing good-naturedly at people who insisted on getting wet and catching pneumonia. 

Prompto grinned, kicked off his boots, and dove smoothly over the side and into the water.

**Notes for the Chapter:**

> There will be one more chapter to this. I'm hoping to have it out by the end of MerMay.


	3. Chapter 3

**Notes for the Chapter:**

> Did I say MerMay? Uhh... Oops.

Through mysterious connections he would not explain, Ignis acquired them a cottage far enough down the shore from the Quay proper that the merpeople could come and go with only a little wariness, yet close enough that one of the humans could walk into town when they needed supplies. Prompto ran errands for Coctura at the Pearl and sometimes for a jewelsmith named Dino who hung around. Aranea found the town's doctor, and through a combination of not taking no for an answer and being genuinely skilled got herself hired on to assist him.

And Ignis... mostly hung around on the shore outside their cottage, as far as Prompto could tell. 

Prompto knew, vaguely, that Noctis and the others were trying to come up with a plan to take back their home from Noctis' uncle. He could sit and listen to Noctis and Iris talk about it for hours; the glittering spires and shining coral buildings, inlaid with shells and polished stone mosaics, the wide white sand plazas and forests of kelp, the bright fish that darted like birds. 

But he was a lot fuzzier on the politics, what exactly it _meant_ that Noctis was Priest to Leviathan, what their magic did, why Noctis' uncle had been able to take it away and how they were planning to take it back. 

"He murdered his own brother," Luna told Prompto one evening, sounding tired. They were sitting on a flat rock just above the water line, where Prompto could stay mostly dry and Luna could have her tail submerged. There was a bag of seaglass sitting between them, and they were picking out the best pieces and polishing them up so Prompto could take them to Dino in the morning. 

At Prompto's wide-eyed, questioning look, Luna sighed. "Ardyn, Noctis' uncle. He murdered Noctis' father, the former High Priest. Half the palace died in the attack, and Noctis only escaped because he tapped into the power of Leviathan herself and created a water spout strong enough that not even Ardyn could get past it for a time." 

"Oh," Prompto gulped. "...I still don't understand why the Tidemother would let that happen." 

"Because she only wants the strongest. Right now, that's Ardyn. But not for long." Luna's jaw tightened in determination, and Prompto wished there was something, anything he could do to help. 

Because as fuzzy as he was on the politics, he wanted to learn more. The Tidemother's Children were _fascinating_. They slept during the day, mostly, somewhere down under the rocky shore. At night they would surface, sitting on the sand or the rocks to talk, hunting fish out in the ocean, or splashing and playing with each other. The cottage sat behind a series of rocky shoals, so boats couldn't come close and it created a safe little cove with almost no fear of discovery. Prompto had always been something of a night owl himself, so it suited him pretty well. 

A few nights after they'd settled into the cottage, Prompto woke in the middle of the night. For a moment he lay blinking up into the darkness of the bedroom he shared with Ignis, wondering what had woken him. 

Then it came again, a high, haunting cascade of notes, like a birdsong but _liquid_ , beautiful enough to take his breath away. 

He sat up, and saw that Ignis was standing by the open window. He glanced over and motioned for Prompto to join him, the moonlight making him look much older and sadder than he was. Obediently, Prompto slipped out of bed and crept over to the window. 

Their entire collection of merpeople - everyone, so far as they knew, who was loyal to Noctis - were down in the cove. Nyx and Crowe and Libertus and Pelna were a small knot of tangled arms and tails and solidarity to one side, Nyx's shoulders heaving silently in a way Prompto had never seen. Iris had her face hidden in Gladio's neck, her tail looped around his waist tightly as though afraid he would slip away too. He had his arms around her just as tightly, his battered expression plain even from the distance. Likewise, Ravus had Luna cradled protectively in his arms, gently stroking fingers through her hair and his usually stern expression slack. Even Cor, the mysterious tentacled cecaelia that Prompto hadn't actually _met_ yet because he preferred to stay in the deeper waters was there, just his head and shoulders above the water. His back was pressed against the rock where Noctis was sitting and his head tipped forward, like all the ocean's weight was around his neck. 

Noctis was perched on one of the flat stones, his back arched forward and his head tipped back, his tail curled almost in on itself, and he was singing. It was beautiful and bitterly sorrowful all at once, an endless rising and falling of notes, like the tides breaking against the rocks, a haunting melody that would drift through Prompto's dreams for months. 

Prompto swallowed hard, realizing there were tears on his cheeks, but when he looked over at Ignis he was somehow not surprised that the other man's eyes were wet too. "What... what's going on?" he whispered, afraid speaking any louder would shatter Noctis' song. 

"It's a requiem," Ignis said equally softly, his eyes dark with his own sadness. "For his father, and Gladio and Iris' father and mother, and Nyx's little sister, and a dozen others that I don't know about." 

"Oh," Prompto's heart broke a little, and he and Ignis stayed at the window, keeping silent watch for the rest of the night. 

They were living in Galdin Quay for almost two months before Prompto found out why Ignis always wore long sleeves and gloves. He'd caught a glimpse of it that night at the window, Ignis wearing short sleeves for bed, rubbing his fingers restlessly over the back of his wrist. But Prompto had been too distracted to properly pay attention, too sad on Noctis' behalf to notice the way Ignis' skin glimmered strangely in the moonlight. 

Every morning before sunrise - which meant usually well before Prompto was awake - Ignis went for a swim. By the time Prompto got up, Ignis was fully dressed and down in the kitchen preparing breakfast for himself and Prompto and Aranea. But one morning, as summer started to cool down toward autumn, Prompto got up a little early, or Ignis slept a little late, or perhaps it was a bit of both. 

When Prompto came downstairs, Ignis was stepping in from outside, wearing sweats slung low on his hips and no shirt, the arm of his glasses held in his teeth as he toweled vigorously at his hair. With the towel over his head he didn't immediately notice Prompto hovering wide-eyed at the foot of the stairs, giving Prompto plenty of time to stare. 

Ignis' skin was as pale as Prompto's, though lacking in the overabundance of freckles. For a long few seconds Prompto thought it was stray water droplets glistening on Ignis' forearms and sides, until he took a closer look and saw the iridescent purplish scales for what they were. 

"What...?" he asked, and Ignis froze for a second, before sighing and dropping the towel down around his shoulders. He took his glasses out of his teeth and slid them on, giving Prompto an unimpressed look for his staring. 

"Dude," Prompto flailed a little, hopping off the last step and crossing the small room to peer more closely at Ignis' arm. Ignis let him, his annoyed look starting to soften into something like amusement. The scales were thickest on his forearms, little irregular diamond patterns that tapered off into scattered single scales here and there across his shoulders, starting to thicken again a little more down his spine. "What the hell?" Prompto looked up at him, eyes nearly round. "Are you a merperson cursed to walk on land or something? Like in that old nursery story? You fell in love with a human and traded your voice to a sea-witch in return for legs? Oh, except you talk all the time. Hm." 

Ignis actually laughed, a quiet cough of amusement as he reached out and ruffled Prompto's hair lightly. "No," he said, an odd, quiet note in his voice that made Prompto look up at him again. There was a slight smile hovering on the corner of Ignis' mouth, and he wasn't looking at Prompto, but rather at the scales on his arm. "No, exactly the opposite. Haven't you heard the Altissian legends about the Tidemother's Children? This is what happens when you fall in love with the sea." 

"The sea?" Prompto repeated doubtfully. He thought back to a week ago, when he'd come home from an errand to find Ignis sitting on a rock, with Gladio half out of the water beside him, strong arms wrapped around Ignis' waist. How Ignis had smiled in a way Prompto had never seen before, one hand caressing Gladio's cheek as he leaned down to kiss him without any fear of the merman's sharp teeth, his other hand running fingers along the spine of one of Gladio's fins and making him shudder. How Prompto had tiptoed away, quite sure that was something he wasn't supposed to witness. "In love with the sea, or in love with someone _in_ the sea?" 

Ignis' quiet smile gave him the only answer he needed. 

"Not all of us used to be human," Noctis clarified for him about a week later. Prompto had been gone for a few days digging some gem samples out of an inland canyon for Dino and only just gotten back. The pay had been nice, but Prompto had found he missed the sea - and the ones in the sea - much more than he'd thought he would. As soon as he got back he'd come down to the shoreline and Noctis practically sat on him, draping his heavy tail across Prompto's legs as though making sure he wasn't about to get up and leave again. It was the first chance Prompto had gotten to ask about Ignis and his scales. "That's why he goes for a swim every day. Eventually, being immersed in salt water will trigger a complete change, tail and all. It's actually really rare, Iggy is only the second one I've met." 

"Who was the first?" Prompto asked, before realizing that might be a sensitive question with all the losses Noctis has incurred in the last few months, and slaps a hand over his own mouth. "Forget I said that, you don't have to answer." 

The look Noctis gave him was sad, but amused too. The pain was still fresh and raw, but faded a little with every tide, his sorrow washed out to sea to mingle with his ancestors in the great dark depths where only Leviathan herself could go. "It's okay. Better you asked me than Gladio or Iris, it was their father who used to be human. He used to joke with Gladio that it must run in the family." 

"That explains the flower names, I wondered about that," Prompto nodded thoughtfully, and Noctis chuckled in agreement. "That's so amazing. Their mother must have been beautiful, for a human to fall in love with her." 

"It wasn't their mother, that came later," Noctis leaned back on his elbows, tipping his head back to look up at the starry sky. "I don't know the story, they never talked about it much, but I could see it every time they looked at each other. Clarus loved Lady Amicitia, but he wasn't _in love_ with her. He jumped into the ocean so he could be with my dad." 

There was such an odd, wistful note in his voice, it made Prompto look over at him instead of following his gaze up to the sky. The moon was waning, but it cast enough light to gleam off the edges of Noctis' fins, pull ghostly highlights out of his dark hair. Staring at his profile, Prompto didn't realize he was reaching until his fingers brushed along the soft, slick skin of Noctis' jaw, and Noctis turned to look at him. 

The glow of his eyes seemed brighter at night, and Prompto had never seen a shade of purer blue. It wasn't blue like the sky or the ocean, it was a blue that defied description, that he could only associate with Noctis. 

Prompto twitched his hand back, an apology ready on his lips, but Noctis moved faster and wrapped his hand gently around Prompto's wrist, guiding his hand in again so Noctis could press the warm, damp skin of his cheek into the curve of Prompto's palm. 

"If your dad looked anything like you," Prompto whispered, heart fluttering stuck in his chest. "I can see why a human would fall in love." 

Noctis smiled, sweet and hesitant and still holding Prompto's wrist in a careful, gentle grip, and that sealed it. 

Five weeks after that, Prompto was standing in front of the mirror in the bathroom, wiping the lather off his face from shaving. He paused, peering more intently at his reflection before a sudden shout from downstairs distracted him. 

He ran out of the bathroom and nearly collided with Aranea in the kitchen doorway. They exchanged wide-eyed looks as the shouting from outside continued, both imagining the worst \- discovery by ill-intended humans, discovery by Ardyn's faction. Prompto snatched his gun out of the rack by the back door and Aranea grabbed her gun-lance, and then they both ran outside. 

The sun was only barely over the horizon, casting everything in bright red-gold, and by the time they both scrambled down the short slope to the pier the commotion was only escalating. There was a froth of churning water about ten feet from the end of the pier, though it slowly calmed as whatever - whoever - was causing it dived deeper. Prompto could see several dark merperson silhouettes moving quickly out toward deeper water, and cast a wild look around. 

Noctis - thank the Six - was sitting on the end of the pier, tail trailing in the water. Iris was flopped out full length across the dock beside him, and as he walked toward them Prompto realized she was laughing, her eyes closed and her fins splayed out and relaxed in a way he'd never seen. Luna hauled herself up to sit beside Iris, also grinning from ear to ear, and she was the one who noticed Prompto and Aranea and waved, her eyes sparkling. 

Iris finally stopped laughing enough to sit up and tip her head back, opening her mouth to let out a high, cascading note that reminded Prompto of birdsong. But it was wilder, more carefree, clearly a happy, celebratory tone that raised goosebumps along Prompto's arms. Luna clapped her hands and added her own voice, and after a moment so did Noctis. 

Noctis was still facing out to sea, so Prompto stepped between Luna and Iris, careful not to impale his ankles on their spines, to sit down beside him. Prompto only just noticed that he was bare-chested and should probably go get a shirt before the sun got too high or he would burn to a crisp. Neither of the women protested his arrival, and when he sat Noctis turned to him with a bright, satisfied expression. It was one that Prompto had never seen before, and it made his heart skip a beat. He wanted Noctis to look that happy all the time. 

"What's going on?" he asked, and Noctis' expression somehow got brighter, holding up Ignis' folded glasses in one hand. Prompto stared at them for a moment, then blinked. "Wait, you mean-?" 

Noctis nodded, turning to keep watch again, even though the waters off their pier were silent for now. "You and 'Nea are our feet on land now; Iggy's change triggered this morning. Gladio's taken him out to deeper waters to help it settle in, and Nyx and Ravus went with them as honor guard." 

"That's amazing," Prompto breathed, though he couldn't imagine what Ignis was going through, having his gills and fins come in and his legs turn to tail. Even if whatever magic of the Tidemother triggered the change kept it from hurting, it was still a massive transformation. 

Though for the sake of the person you loved, Prompto bet you could bare anything. 

"Prompto!" 

Iris' excited shriek jerked Prompto out of his thoughts, and he twisted around to stare at her, bringing a hand up to cover his ear. "Iris, ow, what the hell?" 

She beamed, reaching out to grab his arm and pull it away, down where they could all see. "Noctis, Luna, _look_!" 

She pointed, and then Prompto remembered what he'd noticed in the mirror barely ten minutes ago. Beside him, Noctis sucked in a sharp breath, and wrapped an arm around Prompto's waist. Prompto could feel himself steadily beginning to flush, but there was also a wide, delirious grin spreading across his face. 

Peppered across the back of his forearm, like freckles but a darker, richer copper-gold, were three tiny diamond-shaped scales.

**Notes for the Chapter:**

> And that's it! ^_^ I may write a couple little one-shots and drabbles still set in this 'verse, but this is all for the main meat of it. I hope you enjoyed my little exercise in characterization and (minimal) world-building.


End file.
